Some of the first practical memristive devices are described in U.S. Pat. App. Pub. No. 2008/0090337, entitled “Electrically Actuated Switch,” to R. Stanley Williams. These memristive devices utilize the behavior of nanoscale materials, particularly, a thin film of a material such as titanium dioxide between two electrodes. The electrical properties of the thin films in such a device can be drastically changed through currents that move dopants within the thin films. For example, ion currents can move dopants into an intrinsic material converting the material from its intrinsic or non-conductive state to a conductive semiconductor state. The conductivity between two electrodes can thus be switched from a non-conductive OFF state to a conductive ON state. Electric currents can also move dopants out of the thin films returning the device to its non-conductive state. Devices containing such materials can be used to implement compact, non-volatile switches as described in U.S. Pat. App. Pub. No. 2008/0090337, and in particular, such structures can currently be fabricated with feature sizes on the order of about 10 nm.
Memristors have been proposed for use as memory devices, and practical high density memory architectures using memristive devices are desired.
Use of the same reference symbols in different figures indicates similar or identical items.